Incorrect threshold signature computation in TUF

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

9.3 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2020-6174: 0.99% estimated exploitation activity in the next 30 days; percentile 62.49 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact Metadadata signature verification, as used in tuf.client.updater, counted each of multiple signatures with identical authorized keyids separately towards the threshold. Therefore, an attacker with access to a valid signing key could create multiple valid signatures in order to meet the minimum threshold of keys before the metadata was considered valid. The tuf maintainers would like to thank Erik MacLean of Analog Devices, Inc. for reporting this issue. Patches A fix is available in version 0.12.2 or newer. Workarounds No workarounds are known for this issue. References CVE-2020-6174 Pull request resolving the issue PR 974

Published by the source

21 Aug 2020, 16:25 UTC

Last modified by the source

18 Nov 2024, 22:58 UTC

Source last checked

26 Oct 2026, 13:27 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-pwqf-9h7j-7mv8

2. Revision 2 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-pwqf-9h7j-7mv8

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# Patch Next advisory brief: CVE-2020-6174

Advisory: Incorrect threshold signature computation in TUF
IDs: CVE-2020-6174, GHSA-pwqf-9h7j-7mv8
Record: https://patchnext.com/advisories/cve-2020-6174 (revision 3, source checked 26 Oct 2026, 13:27 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: tuf 0.12.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI tuf: affected < 0.12.2; fixed in 0.12.2

## Suggested inspection (read-only)
- `python -m pip show tuf`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on tuf.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-pwqf-9h7j-7mv8 (OSV record GHSA-pwqf-9h7j-7mv8 lists affected ranges: PyPI tuf >=0 <0.12.2 (fixed))
- Verified: https://github.com/advisories/GHSA-pwqf-9h7j-7mv8 (GitHub-reviewed advisory GHSA-pwqf-9h7j-7mv8 lists affected ranges: PyPI tuf >=0 <0.12.2)

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